Welcome to SR!
I'm sorry for the situation you are in, but honestly it doesn't sound to me like he really WANTS recovery (I'm a recovering crack addict). If he is wanting something in exchange for the needles, he is ASKING for drugs.
Yes, she is influincing him, but it sounds like you are also around her and YOU aren't asking her for any pills.
As hard as it is, there is no way you can make him get clean if he doesn't want it. Personally, if anyone in my family or close friends was using crack, I would have to stay away from them, as it would jeopardize MY recovery.
The best thing you can do is focus on you. I had to leave my XABF (ex-addict-boyfriend) because he was still using. Yes, I was "strong" for a while and didn't use, but it wore me down and I eventually relapsed.
Rehab gave him the tools to live life without drugs, it's up to him whether or not he uses those tools.
It sounds like this is going to be an ongoing thing with him if you continue to stay with him. You started your relationship with using together. In that kind of situation, when one person seeks recovery and the other doesn't, there usually isn't much a relationship left.
Take care of you.
Hugs and prayers!
Amy